"""
Creates an issue that generates a table for dependency checking whether
all packages support the latest Django version. "Latest" does not include
patches, only comparing major and minor version numbers.

This script handles when there are multiple Django versions that need
to keep up to date.
"""
from __future__ import annotations

import os
import re
import sys
from pathlib import Path
from typing import TYPE_CHECKING, Any, Iterable, NamedTuple

import requests
from github import Github

if TYPE_CHECKING:
    from github.Issue import Issue

CURRENT_FILE = Path(__file__)
ROOT = CURRENT_FILE.parents[1]
REQUIREMENTS_DIR = ROOT / "{{cookiecutter.project_slug}}" / "requirements"
GITHUB_TOKEN = os.getenv("GITHUB_TOKEN", None)
GITHUB_REPO = os.getenv("GITHUB_REPOSITORY", None)


class DjVersion(NamedTuple):
    """
    Wrapper to parse, compare and render Django versions.

    Only keeps track on (major, minor) versions, excluding patches and pre-releases.
    """

    major: int
    minor: int

    def __str__(self) -> str:
        """To render as string."""
        return f"{self.major}.{self.minor}"

    @classmethod
    def parse(cls, version_str: str) -> DjVersion:
        """Parse interesting values from the version string."""
        major, minor, *_ = version_str.split(".")
        return cls(major=int(major), minor=int(minor))


def get_package_info(package: str) -> dict:
    """Get package metadata using PyPI API."""
    # "django" converts to "Django" on redirect
    r = requests.get(f"https://pypi.org/pypi/{package}/json", allow_redirects=True)
    if not r.ok:
        print(f"Couldn't find package: {package}")
        sys.exit(1)
    return r.json()


def get_django_versions() -> Iterable[DjVersion]:
    """List all django versions."""
    django_package_info: dict[str, Any] = get_package_info("django")
    releases = django_package_info["releases"].keys()
    for release_str in releases:
        if release_str.replace(".", "").isdigit():
            # Exclude pre-releases with non-numeric characters in version
            yield DjVersion.parse(release_str)


def get_name_and_version(requirements_line: str) -> tuple[str, ...]:
    """Get the name a version of a package from a line in the requirement file."""
    full_name, version = requirements_line.split(" ", 1)[0].split("==")
    name_without_extras = full_name.split("[", 1)[0]
    return name_without_extras, version


def get_all_latest_django_versions() -> tuple[DjVersion, list[DjVersion]]:
    """
    Grabs all Django versions that are worthy of a GitHub issue.

    Depends on Django versions having higher major version or minor version.
    """
    print("Fetching all Django versions from PyPI")
    base_txt = REQUIREMENTS_DIR / "base.txt"
    with base_txt.open() as f:
        for line in f.readlines():
            if "django==" in line:
                break
        else:
            print(f"django not found in {base_txt}")  # Huh...?
            sys.exit(1)

    # Begin parsing and verification
    _, current_version_str = get_name_and_version(line)
    # Get a tuple of (major, minor) - ignoring patch version
    current_minor_version = DjVersion.parse(current_version_str)
    newer_versions: set[DjVersion] = set()
    for django_version in get_django_versions():
        if django_version > current_minor_version:
            newer_versions.add(django_version)

    return current_minor_version, sorted(newer_versions, reverse=True)


_TABLE_HEADER = """

## {file}.txt

| Name | Version in Master | {dj_version} Compatible Version | OK |
| ---- | :---------------: | :-----------------------------: | :-: |
"""
VITAL_BUT_UNKNOWN = [
    "django-environ",  # not updated often
]


class GitHubManager:
    def __init__(self, base_dj_version: DjVersion, needed_dj_versions: list[DjVersion]):
        self.github = Github(GITHUB_TOKEN)
        self.repo = self.github.get_repo(GITHUB_REPO)

        self.base_dj_version = base_dj_version
        self.needed_dj_versions = needed_dj_versions
        # (major+minor) Version and description
        self.existing_issues: dict[DjVersion, Issue] = {}

        # Load all requirements from our requirements files and preload their
        # package information like a cache:
        self.requirements_files = ["base", "local", "production"]
        # Format:
        # requirement file name: {package name: (master_version, package_info)}
        self.requirements: dict[str, dict[str, tuple[str, dict]]] = {
            x: {} for x in self.requirements_files
        }

    def setup(self) -> None:
        self.load_requirements()
        self.load_existing_issues()

    def load_requirements(self):
        print("Reading requirements")
        for requirements_file in self.requirements_files:
            with (REQUIREMENTS_DIR / f"{requirements_file}.txt").open() as f:
                for line in f.readlines():
                    if "==" in line and not line.startswith("{%"):
                        name, version = get_name_and_version(line)
                        self.requirements[requirements_file][name] = (
                            version,
                            get_package_info(name),
                        )

    def load_existing_issues(self):
        """Closes the issue if the base Django version is greater than needed"""
        print("Load existing issues from GitHub")
        qualifiers = {
            "repo": GITHUB_REPO,
            "author": "app/github-actions",
            "state": "open",
            "is": "issue",
            "in": "title",
        }
        issues = list(
            self.github.search_issues(
                "[Django Update]", "created", "desc", **qualifiers
            )
        )
        print(f"Found {len(issues)} issues matching search")
        for issue in issues:
            matches = re.match(r"\[Update Django] Django (\d+.\d+)$", issue.title)
            if not matches:
                continue
            issue_version = DjVersion.parse(matches.group(1))
            if self.base_dj_version > issue_version:
                issue.edit(state="closed")
                print(f"Closed issue {issue.title} (ID: [{issue.id}]({issue.url}))")
            else:
                self.existing_issues[issue_version] = issue

    def get_compatibility(
        self, package_name: str, package_info: dict, needed_dj_version: DjVersion
    ):
        """
        Verify compatibility via setup.py classifiers. If Django is not in the
        classifiers, then default compatibility is n/a and OK is ✅.

        If it's a package that's vital but known to not be updated often, we give it
        a ❓. If a package has ❓ or 🕒, then we allow manual update. Automatic updates
         only include ❌ and ✅.
        """
        # If issue previously existed, find package and skip any gtg, manually
        # updated packages, or known releases that will happen but haven't yet
        if issue := self.existing_issues.get(needed_dj_version):
            if index := issue.body.find(package_name):
                name, _current, prev_compat, ok = [
                    s.strip() for s in issue.body[index:].split("|", 4)[:4]
                ]
                if ok in ("✅", "❓", "🕒"):
                    return prev_compat, ok

        if package_name in VITAL_BUT_UNKNOWN:
            return "", "❓"

        # Check classifiers if it includes Django
        supported_dj_versions: list[DjVersion] = []
        for classifier in package_info["info"]["classifiers"]:
            # Usually in the form of "Framework :: Django :: 3.2"
            tokens = classifier.split(" ")
            if len(tokens) >= 5 and tokens[2].lower() == "django":
                version = DjVersion.parse(tokens[4])
                if len(version) == 2:
                    supported_dj_versions.append(version)

        if supported_dj_versions:
            if any(v >= needed_dj_version for v in supported_dj_versions):
                return package_info["info"]["version"], "✅"
            else:
                return "", "❌"

        # Django classifier DNE; assume it isn't a Django lib
        # Great exceptions include pylint-django, where we need to do this manually...
        return "n/a", "✅"

    HOME_PAGE_URL_KEYS = [
        "home_page",
        "project_url",
        "docs_url",
        "package_url",
        "release_url",
        "bugtrack_url",
    ]

    def _get_md_home_page_url(self, package_info: dict):
        urls = [
            package_info["info"].get(url_key) for url_key in self.HOME_PAGE_URL_KEYS
        ]
        try:
            return f"[{{}}]({next(item for item in urls if item)})"
        except StopIteration:
            return "{}"

    def generate_markdown(self, needed_dj_version: DjVersion):
        requirements = f"{needed_dj_version} requirements tables\n\n"
        for _file in self.requirements_files:
            requirements += _TABLE_HEADER.format_map(
                {"file": _file, "dj_version": needed_dj_version}
            )
            for package_name, (version, info) in self.requirements[_file].items():
                compat_version, icon = self.get_compatibility(
                    package_name, info, needed_dj_version
                )
                requirements += (
                    f"| {self._get_md_home_page_url(info).format(package_name)} "
                    f"| {version} "
                    f"| {compat_version} "
                    f"| {icon} "
                    f"|\n"
                )
        return requirements

    def create_or_edit_issue(self, needed_dj_version: DjVersion, description: str):
        if issue := self.existing_issues.get(needed_dj_version):
            print(f"Editing issue #{issue.number} for Django {needed_dj_version}")
            issue.edit(body=description)
        else:
            print(f"Creating new issue for Django {needed_dj_version}")
            issue = self.repo.create_issue(
                f"[Update Django] Django {needed_dj_version}", description
            )
            issue.add_to_labels(f"django{needed_dj_version}")

    def generate(self):
        for version in self.needed_dj_versions:
            print(f"Handling GitHub issue for Django {version}")
            md_content = self.generate_markdown(version)
            print(f"Generated markdown:\n\n{md_content}")
            self.create_or_edit_issue(version, md_content)


def main() -> None:
    # Check if there are any djs
    current_dj, latest_djs = get_all_latest_django_versions()
    if not latest_djs:
        sys.exit(0)
    manager = GitHubManager(current_dj, latest_djs)
    manager.setup()
    manager.generate()


if __name__ == "__main__":
    if GITHUB_REPO is None:
        raise RuntimeError(
            "No github repo, please set the environment variable GITHUB_REPOSITORY"
        )
    main()